We report the observation of second order Bragg resonance(2 nd-OBG) produced by tilted fiber gratings(TFGs) fabricated using phase mask UV inscription.The theoretical analysis has revealed that the generation of high ...We report the observation of second order Bragg resonance(2 nd-OBG) produced by tilted fiber gratings(TFGs) fabricated using phase mask UV inscription.The theoretical analysis has revealed that the generation of high order Bragg resonance of gratings is induced by a square-shape refractive index profile,which is caused by over-saturated UV exposure.In the experiment,we have studied the TFGs with different tilt angles under over-saturated UV exposure,in which all gratings have showed the 2 nd-OBR,and the larger tilt angle of the grating has the stronger 2 nd-OBR.When the tilt angle of the grating is-45°,the Bragg resonance exhibits very strong polarization dependence,because the 2 nd-OBR wavelength is located within the polarizing bandwidth of 45° TFG.Finally,we have demonstrated an erbium-doped fiber laser with> 99.9% degree of polarization,and,by applying mechanical stretching on the grating,a wavelength tunable laser output has been achieved.The output laser shows ~0.2 dB amplitude variation within 1 h continuous monitoring of the laser.展开更多
基金supported in part by the National Natural Science Foundation of China (No. 62075071)the National Science Fund for Excellent Young Scholars (No. 61922033)+1 种基金the ‘111’ Project (No. D20031)the Shenzhen-Hong Kong Science and Technology Innovation Cooperation Zone applied fundamental research project (No. HZQB-KCZYB-2020082)
文摘We report the observation of second order Bragg resonance(2 nd-OBG) produced by tilted fiber gratings(TFGs) fabricated using phase mask UV inscription.The theoretical analysis has revealed that the generation of high order Bragg resonance of gratings is induced by a square-shape refractive index profile,which is caused by over-saturated UV exposure.In the experiment,we have studied the TFGs with different tilt angles under over-saturated UV exposure,in which all gratings have showed the 2 nd-OBR,and the larger tilt angle of the grating has the stronger 2 nd-OBR.When the tilt angle of the grating is-45°,the Bragg resonance exhibits very strong polarization dependence,because the 2 nd-OBR wavelength is located within the polarizing bandwidth of 45° TFG.Finally,we have demonstrated an erbium-doped fiber laser with> 99.9% degree of polarization,and,by applying mechanical stretching on the grating,a wavelength tunable laser output has been achieved.The output laser shows ~0.2 dB amplitude variation within 1 h continuous monitoring of the laser.
